I need to check the belts on my Ender 3 to confirm they are properly set up, functioning, and undamaged. How do I go about doing this?
Loosen the screws holding the far right hand side of the belt cog in place on the gantry, tighten the belt by moving the cog outwards until the belt looks horizontal, tighten the screws back up and test. It's a pretty intuitive procedure.
To see if the belt is OK, just visually inspect it. It's just a belt, if it has splits or something then it has issues.